Adhesive composition

ABSTRACT

An adhesive composition for bonding polished metal surfaces to vinyl chloride polymer coated metal substrates is disclosed which is comprised of a thermoplastic vinyl chloride polymer resin, a thermosetting epoxy resin normally incompatible with the vinyl chloride polymer resin and an amount of an acrylonitrile/butadiene/styrene copolymer which imparts compatibility between the epoxy resin and the vinyl chloride polymer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an adhesive for metals and more particularlyto an adhesive for metal containers in which the end and body membersare joined through a lap seam.

2. The Prior Art

There has been developed metal containers formed from aluminum and steelof the two-piece type which are formed from a dome-shaped end memberhaving a depending annular lip or skirt and a body member, the bodymember being a seamless cylinder having an integral bottom, the open endof the body member being formed to be inserted in telescopingrelationship with the annular lip of the end, the overlapping sectionsof annular lip of the end and the open body section being bondedtogether to form a leakproof joint by the interposition of a suitableadhesive between the opposed faces of the end and open body sections.

In copending application Ser. No. 191,226, filed Sept. 26, 1980, in thename of Donald J. Roth, the disclosure of which is incorporated hereinby reference, there is disclosed a two-piece container of this typesuitable for use in the packaging of carbonated beverages such as beerand soft drinks wherein the end member is of a relatively short lengthcompared with the body member, the end member being comprised of aconical section with a central pour opening and a toroidal peripheralsection about the conical section and annular lip or skirt dependingtherefrom. The upper, open end of the body member is necked in to forman axially extending cylindrical portion or annulus of a diameterreduction to complementarily fit into the lip of the end, the outersurface of the annulus being adhesively bonded to the inner surface ofthe end lip to form a lap joint between the annulus and lip sections ofthe body and end members.

The end and body members have wall thicknesses less than 10 mils and arepliable without permanent deformity to accommodate laterally imposedloads. When the assembled container is filled with a carbonatedbeverage, the adhesively bonded end reacts to the internal forcesgenerated by the pressurized beverage to expand into a spherical shapewhereby the lip is caused to be beamed radially inwardly against theannulus section of the body. The forces tending to expand the end memberare thereby utilized to produce a compressive force radially inwardly onthe lip together with the tensile forces exerted by the pressurizedbeverage tending to expand the upper end of the body insures aparallelism between body and lip portions precluding the development ofvoids which would produce leaking joints. The force couple createdbetween the lip and the necked in body portions causes the adhesiveinterposed therebetween to be held in compression whereby peeling forceson the bonded lap joint are minimized or substantially eliminated.

The construction of the two-piece containers disclosed in Ser. No.191,226 lends itself to high speed production in which an adhesivecomposition dispersed in a volatile solvent is applied, usingconventional coating techniques such as brush, roll coating or gravurecoating, is either applied to the outer surface of the annulus of thenecked in body section or to the inner surface of the end lip prior toassembly of the end and body members or both the annulus and the lip.After application of the adhesive, the coated member is heated tovolatilize the solvent media in which the adhesive is dispersed and theend member is guided into an interference fit assembly with the annulusof the necked-in body section. After assembly, the container is heatedto an elevated temperature to the softening temperature of the adhesiveto cause the adhesive to bond the assembled end and body members.

The high strength adhesives known to the art have not been totallysuccessful in bonding the end and body portions of the two-piececontainers discussed above for a number of reasons. Some of the majorreasons are that although these adhesives have excellent cohesivestrength, they are deficient either in their adhesion to the outer metalsurface of the annulus or to the coated interior surface of the end lip.

The body member of the two-piece container of Ser. No. 191,226 isreadily fabricated by the well-known drawn and wall ironing process. Thebody members fabricated by this process have outer wall surfaces whichare highly polished and extremely smooth which makes it difficult toeffectively bond thermoplastic adhesives such as polyvinylchloride tosuch surfaces. Although vinylchloride polymer adhesives are extremelycompatible and will strongly bond to the vinylchloride polymer coatingsconventionally used as interior coatings for beverage containers, suchadhesives will not adhere effectively to the polished exterior surfaceof the drawn and wall ironed container body. As the construction of thetwo-piece container of Ser. No. 191,226 requires that the outer surfaceof the annulus of the necked-in section of the body be overlapped andbonded to the interior coated surface of the end, thermoplasticadhesives such as polyvinylchloride, polyethylene, polypropylene do notform adhesive bonds with the reliability required in the manufacture ofcontainers used in the packaging of carbonated beverages.

Attempts at using thermosetting resin compositions such as those basedon epoxy resins have revealed that although such compositions willstrongly adhere to polished metal surfaces of the character found on theouter surfaces of drawn and wall ironed container bodies, such adhesivesdo not have sufficient adhesion to coated metal surfaces of the typefound in the interior surfaces of containers used for packagingcarbonated beverages, e.g., vinyl chloride polymer coated metalsubstrates, to provide an adhesive bond of the reliability required inthe manufacture of containers used for the packaging of carbonatedbeverages.

It would be desirable if the excellent adhesion of thermoplastic resinssuch as vinyl chloride polymers to internal coated metal surfaces couldbe combined with the polished surface adhesion of thermosetting resinssuch as epoxy resins to obtain an adhesive formulation which wouldadhere tenaciously both to polished metal surfaces as well as coatedmetal substrates.

Attempts to disperse a combination of thermosetting resins such as epoxyresins and thermoplastic resins such as vinyl chloride polymers in acommon dispersion media have not been successful as the two resin typesare incompatible with the result that unstable dispersions result whichrapidly stratify on standing, thereby rendering the dispersionsunsuitable for commercial practice.

SUMMARY OF THE INVENTION

In accordance with the present invention adhesive formulations areprepared by effecting the compatibility of thermoplastic vinyl chloridepolymer resins and thermosetting epoxy resin formulations by the use ofa third component compatible with both the thermosetting epoxy resin andthe thermoplastic vinyl chloride polymer resin, the third componentbeing an acrylonitrile/butadiene/styrene (ABS) copolymer.

The adhesive formulation of the present invention may be obtained as astable dispersion of resin solids in a fugitive organic solvent whichmay be applied as such to either the outer polished surface of aseamless drawn and wall ironed container body or the vinyl chlorideorganosol coated interior surface of an end member. After application,the container member is heated to volatilize the solvent. After assemblyof the container members, the adhesive solids interposed between theopposed faces of the inner surface of a vinyl chloride polymer coatedmetal substrate and the outer surface of a polished metal member and thelap joint formed therebetween is thereafter heated to the softeningtemperature of ABS copolymer. The mixture of adhesive solids is causedto adhere tenaciously to the polished metal surface and the coated metalsurface whereby a lap joint having exceptionally high bursting or hoopstrength is achieved.

Examination of the metal surfaces to which the adhesive admixture of thepresent invention is applied indicates that upon heating the appliedfilm of adhesive resin solids, the thermosetting epoxy resin is advancedrapidly to the insoluble stage because of the heat applied and formsadherent, individual particles of the thermoset epoxy resin on thepolished metal surface area to which the adhesive dispersion is applied.The adherence of the thermoset particles on the smooth surfaced metalcreates a roughened or sandpaper effect on the metal surface andprovides anchor points on the metal surface whereby the thermoplasticresins in the admixture, still soft from the heated condition of thesurface, are adhered to the anchored thermoset particles.

After the lap joint to which the adhesive has been applied is cooled,the solidified thermoplastic resins being anchored to the thermosetparticles on the outer metal surface of the container body andadhesively adhered to the inner coated metal surface of the endcohesively bonds the joint to form a leakproof unitary structure.

PREFERRED EMBODIMENTS

The metal surfaces to which the adhesive compositions of the presentinvention may be applied include coated and uncoated aluminum or lowcarbon steel with or without an external plating of chromium, nickel ortin.

The term "vinyl chloride polymer" as used herein means resins producedby the polymerization of vinyl chloride or by copolymerization of vinylchloride and minor amounts of other monomers such as vinyl acetate andesters of acrylic and methacrylic acids with the lower aliphaticalcohols up to n-butyl alcohols as well as hydrolyzed vinylchloride-vinyl acetate copolymers and terpolymers such as vinylchloride-vinyl acetate-maleic acid. The vinyl chloride copolymers usedin the practice of the present invention are advantageously comprised ofabout 70 to about 95% by weight vinyl chloride and about 5 to about 25%by weight of the comonomer.

The epoxy resin component of the adhesive compositions of the presentinvention are complex polymeric epoxy-hydroxy ethers resulting from thecatalyzed reaction of a polyhydric phenol with an excess of an epoxide,e.g., epihalohydrins and alkylene oxides, as described in U.S. Pat. Nos.2,456,408 and 2,592,560. The principal product of this reaction is aresinous epoxy glyceryl polyether comprising epoxy glyceryl (glycidyl)radicals or hydroxyl substituted glyceryl radicals alternating with thedivalent residue of the polyhydric phenol, which radicals are united ina chain through ether oxygen atoms.

In the present invention, those epoxy resins which are of relativelyhigh molecular weight are utilized in preparing the adhesivecomposition. Generally, epoxy resins having an average molecular weightin the range of 1400 to 5000 may be used.

Epoxy resins are available commercially. Preferred examples are EPON1004 and EPON 1007, products of Shell Chemical Company, which are thecondensation products of epichlorhydrin and Bisphenol A(dihydroxy-diphenyl-dimethyl methane) and have a respective epoxy assayof 875 to 1025 and 2500 to 4000 grams of sample per gram mole of epoxygroup (gram/gram mole). The average molecular weight of an epoxy resinis approximately twice the epoxy assay.

To accelerate hardening during the period the adhesive composition isheated, the epoxy resin is combined with a minor amount of a heatactivatable aminoplast cross-linking resin. Generally about 70 to about90 percent by weight of the epoxy resin is combined with about 10 toabout 30 percent by weight of the aminoplast resin when the epoxy resinis used as a component in the adhesive compositions of the presentinvention.

Examples of aminoplast resins include urea-aldehyde and triazinealdehyde resins and alcohol modified derivatives thereof, that is,alkylated amino resins wherein the alkyl radical contains from 2 to 8carbon atoms. Such aminoplast resins are the reaction products ofaldehydes, for instance formaldehyde, acetaldehyde and the like, withurea, substituted ureas, thioureas, ethylene urea, melamine,benzoquanamine, acetoguanamine and the like. The resulting methylolsubstituted products are etherified with alcohols, for exampleisopropanol, butanol and 2-ethyl hexanol, in order to obtain stabilityand organic solubility. Such organic soluble aminoplast resins arecontemplated for use in this invention and butylated urea formaldehyderesins are preferred for use in the practice of the present invention.

The ABS copolymers used in the practice of the present invention areknown to the art. The ABS copolymers are thermoplastic polymers producedeither by blending styrene-acrylonitrile copolymer resins with butadienebased elastomers or by grafting styrene and acrylonitrile monomers ontopolybutadiene or butadiene-styrene or butadiene-acrylonitrilecopolymers. The specific procedures for preparing ABS graft copolymersare also well known to the art, e.g., U.S. Pat. Nos. 2,908,661 and3,496,250. A graft copolymer is a polymer prepared by first polymerizinga monomer (or a mixture of monomers) with subsequent polymerization of asecond monomer or group of monomers onto the product of the firstpolymerization. The first polymerization prepares what is hereinafterreferred to as the rubbery backbone.

The specific graft copolymers utilized in this invention are prepared byfirst polymerizing a conjugated diene such as butadiene in the presenceof a monovinyl aromatic hydrocarbon such as styrene and/or acrylonitrileto provide a polymerized diene rubbery backbone. Thereafter, a secondmonomer or group of monomers are grafted onto the rubbery backbone tocomplete the graft copolymer. This is accomplished by the addition andinteraction under polymerization conditions of an acrylonitrile,substituted acrylonitrile and a monovinyl aromatic hydrocarbonexemplified by acrylonitrile and styrene.

The backbone, i.e., conjugated diene polymer or copolymer, is preparedso as to comprise about 10% by weight to about 60% by weight andpreferably 10 to about 30% by weight of the total copolymer compositionand the acrylonitrile and styrene monomers that are polymerized in thepresence of the backbone polymer or copolymer comprises from about 40%by weight to about 90% by weight of the total composition.

The acrylonitrile or component of the copolymer preferably comprisesabout 10 to about 30% by weight of the three-component organic mixtureand the styrene component comprises from about 40 to about 70% by weightof the total composition.

The term styrene when used in the present application includes withinits meaning styrene, α-methylstyrene, vinyl toluene, vinyl xylene,ethylvinylbenzene, isopropylstyrene, chlorostyrene, dichlorostyrene,ethylchlorostyrene and mixtures thereof.

The term acrylonitrile when used in the present application includeswithin its meaning acrylonitrile, methacrylonitrile, chloroacrylonitrileand mixtures thereof.

ABS graft copolymers are commercially available. An ABS graft copolymersold under the tradename Cycolac GSM and available from the Borg WarnerCorporation has a composition determined to consist of 54.5±2.0%styrene, 21.5±2.0% acrylonitrile and 24.5±1.0% butadiene. Other ABSgraft copolymers available from the Borg Warner Corporation includeCycolac ADG which consists of 60.5±2.0% styrene, 20.5±2.0% acrylonitrileand 18.0±2.0% butadiene and Cycolac DFA which consists of 59.5±2.0%styrene, 20.5±2.0% acrylonitrile and 19.0±2.0% butadiene.

When used in the manufacture of containers in the practice of thepresent invention the selection of proportions of thermosetting epoxyresin, vinyl chloride polymer resin and ABS copolymer depends on thecharacter and type of the metal surface, the thickness of the adhesivefilm required for cohesion of the lap joint and the limits ofcompatibility between the thermosetting epoxy resin and thethermoplastic vinyl cloride polymer resin.

The quantity of the thermosetting epoxy resin present in the adhesivecomposition of the present invention should be at least about 5% basedon the solids weight of the adhesive composition so that there is anadequate amount of the resin material to create the roughened, sandpapereffect on the polished metal surface in which the adhesive is in contactduring the heating of the lap joint. Generally the thermosetting epoxyresin comprises about 5 to 30% by weight of the solids content of theadhesive composition and preferably about 10 to about 20% by weight. Ifan amount of epoxy resin in excess of 30% by weight is used in theadhesive formulation of the present invention, the sandpaper effect islost and poor adhesion of the vinyl chloride polymer to the metalsurface results.

The quantity of the thermoplastic vinyl chloride polymer present in theadhesive composition of the present invention should be at least about10% by weight based on the solids weight of the adhesive composition sothat there is an adequate amount of the vinyl chloride polymer tocohesively adhere the opposed surfaces of the lap joint. Generally thevinyl chloride polymer comprises about 15 to about 70% by weight of thesolids content of the adhesive composition and preferably about 20 toabout 65% by weight.

The adhesive composition of the present invention is applied as adispersion of the epoxy and vinyl chloride polymer resins in a fugitiveorganic liquid. The quantity of the ABS resin incorporated in theadhesive composition of the present invention should be at least about20% by weight based on the solids weight of the adhesive composition.The incorporation of the ABS copolymer in the adhesive dispersion iscritical to obtaining a stable dispersion of the vinyl chloride polymerand epoxy resins. In the absence of the ABS copolymer, the vinylchloride polymer and epoxy resin components of the dispersion begin tostratify and separate from the dispersion about 1/4 hours after thedispersion is prepared whereas when the ABS copolymer is present in theadhesive dispersion no stratification or other separation of the solidscomponents occurs even 5 days after preparation of the dispersion.Generally the thermoplastic ABS copolymer comprises about 20 to about85% by weight of the solids content of the adhesive composition andpreferably about 30 to about 50% by weight.

The resin solids present in the adhesive dispersions of the presentinvention is comprised of about 5 to about 30% by weight and preferablyabout 10 to about 20% by weight of the epoxy resin, about 0.25 to about7.5% by weight and preferably about 1 to about 6% by weight of anaminoplast condensate cross-linking agent, about 10 to about 70% byweight and preferably about 20% to about 65% by weight of the vinylchloride polymer and about 20 to about 85% by weight and preferablyabout 30 to about 75% by weight of the ABS copolymer.

The solvent compositions in which the resin components of the adhesivecomposition of the present invention are dispersed are not especiallycritical. It is necessary, however, that the solvents be volatile at thetemperatures at which the lap joint is heated after application theretoof the adhesive dispersion. Suitable solvents comprise aryl or aralkylhydrocarbons blended with oxygen containing solvents such as alcohols,ketones, ethers or esters and mixtures thereof. Alcohols, ketones,ethers and esters or mixtures thereof can be used with or without thearyl or aralkyl hydrocarbons. Solvent systems comprising a mixture ofaryl or aralkyl hydrocarbons and alcohols yield dispersions havingoptimum viscosity for application and for this reason are preferred.

Examples of the aromatic hydrocarbon solvents are xylene, toluene andpetroleum fractions having a boiling range of 120° to 200° C. Examplesof suitable oxygen containing solvents are acetone, methyl ethyl ketone,butanol, diacetone alcohol, isophorone, methyl isobutyl ketone,nitropropane, butyl cellosolve, tetrahydrofuran, cyclohexanone, amylacetate, methyl cellosolve acetate, diisobutyl ketone and cyclohexanol.

The solvents selected to prepare the adhesive dispersion should becapable of forming a common dispersion medium of the individual resincomponents of the adhesive composition and for this purpose differentsolvent media may be employed for the resin components insofar as suchsolvent media will blend or mix together and carry their respectivesolutes compatibly into the common dispersion.

In preparing the adhesive dispersion, the vinyl chloride polymer resin,epoxy resin and acrylonitrile/butadiene/styrene copolymer are separatelydissolved in suitable solvent systems formed of solvents selected fromamong those mentioned above and they are combined to obtain an adhesivedispersion suitable for application to the surfaces of the end and bodycomponents which are to be overlapped to form two-piece containers.

The adhesive compositions of this invention can be satisfactorilyapplied at a solids content ranging from about 15 to about 40% byweight, based on the total weight of the dispersion. Generally, a solidscontent of about 20 to about 30% by weight is preferred.

The dispersion can be satisfactorily applied by any of the conventionalmethods employed in the coating industry. However, brush, gravure ordirect roller coating are preferred methods, as the desired adhesiveweight is easily and conveniently applied. Spraying, dipping and flowcoating are also useful methods of applying the adhesive dispersion.

In the fabrication of two-piece containers using the adhesivecomposition of the present invention the adhesive is applied either tothe outer surface of the annulus of the necked in section of thecontainer body or to the inner surface of the lip of the end prior tothe assembly of the end to the annulus of the body member or both sothat after assembly the assembled container is heated to effecthardening of the epoxy resin component of the adhesive during which timethe end and body members of the assembled container may be moved axiallyor circumferentially relative to each other to eliminate any pinholes orthe like formed in the adhesive and to promote good adhesion of theadhesive solids to the metal members. Upon cooling, the solidifiedthermoplastic resin components of the adhesive bond the overlapped metalmembers together.

The heating condition to which the overlapped joint is exposed to effecthardening of the epoxy resin and volatilization of the dispersionsolvents is normally a temperature of about 175° to about 320° C. for aperiod of about 20 minutes to about 1 minute.

The adhesive film thickness generally employed for bonding the lappedmetal parts is in the range of about 0.001 to 0.003 inches.

The following example is set forth merely as an illustration of theinvention and is not intended to limit the scope thereof.

EXAMPLE

Resin solutions were prepared as follows:

    ______________________________________                                                             Percent by Wt.                                           ______________________________________                                        (A) EPOXY RESIN SOLUTION (20% Solids)                                         Solids                                                                        Epichlorohydrin-Bisphenol A                                                                          17.0                                                   Urea-Formaldehyde Resin                                                                              3.0                                                    Solvents                                                                      Toluene                41.3                                                   Isopropyl alcohol      18.5                                                   Diacetone alcohol      10.9                                                   Xylene                 6.8                                                    Butyl Cellosolve       1.7                                                    n-butanol              1.7                                                    (B) VINYL CHLORIDE POLYMER SOLUTION (37.5% Solids)                            Solids                                                                        Polyvinylchloride      22.5                                                   Vinylchloride/vinylacetate copolymer                                                                 11.3                                                   Phenol-formaldehyde resin*                                                                           3.8                                                    Solvents                                                                      Solvesso 150 (aromatic)                                                                              27.3                                                   Cellosolve acetate     13.6                                                   Dibutyl ketone         9.1                                                    Butyl carbitol         2.3                                                    Xylene, butyl alcohol  Remainder                                              (C) ACRYLONTRILE/BUTADIENE/STYRENE                                            COPOLYMER SOLUTION (45% Solids)                                               Component                                                                     Acrylonitrile/butadiene/styrene graft                                         copolymer (Cycolac GSM)                                                                              45                                                     Acetone                55                                                     ______________________________________                                         *Heat Stabilizer                                                         

Varying amounts of the three resin solutions A, B and C were thencombined to prepare adhesive dispersions as follows:

    __________________________________________________________________________    ADHESIVE DISPERSION                                                                 Component     Component     Component                                   Adhesive                                                                            A             B             C                                           Dispersion                                                                          Liq. Parts                                                                             Wt. % of                                                                           Liq. Parts                                                                             Wt. % of                                                                           Liq. Parts                                                                             Wt. % of                           No.   % by wt.                                                                           Solids                                                                            Total                                                                              % by wt.                                                                           Solids                                                                            Total                                                                              % by wt.                                                                           Solids                                                                            Total                              __________________________________________________________________________    1     20   4.0 10.8 30   15.0                                                                              40.5 40   18.0                                                                              48.7                               2     20   4.0 11.3 60   22.5                                                                              63.4 20   9.0 25.3                               3     20   4.0 10.4 20   7.5 19.5 60   27.0                                                                              70.1                               4     30   6.0 17.0 30   11.25                                                                             31.9 40   18.0                                                                              51.1                               5     30   6.0 17.4 40   15.0                                                                              43.5 30   13.5                                                                              39.1                               6     33.3 6.67                                                                              19.5 33.3 12.5                                                                              36.6 33.3 15.0                                                                              43.9                               7     30   6.0 17.8 50   18.75                                                                             55.5 20   9.0 26.7                               __________________________________________________________________________

The admixture of the resin solutions was agitated to prepare a stabledispersion of resin components. No separation of resin components wasnoted 5 days after preparation of the dispersions whereas in similarlyprepared dispersions in which the ABS copolymer was not included resincomponent separation was noted after about 2 hours.

Adhesive dispersions Nos. 1-7 were used to bond the end and body membersof 6 ounce two-piece containers formed of 3004-H19 aluminum in whichportions of a domed end and one-piece seamless body members wereassembled, overlapped and bonded to each other to form the container.The body member was a polished, seamless cylinder of 4-13/16 inchlength, 21/2 inch diameter and 10 mils thickness having an integralbottom. The body member at its upper end was necked-in to provide aradially inwardly extending shoulder about 1/16 inch wide and about theinner portion of which extended an annulus of approximately 1/8 inch inlength. The outer surface of the body member had a smooth, polishedsurface. The annulus of the necked in section was adapted for aninterference fit into the lower lip portion of the domed end, the lipportion being about 0.837 inch in total axial depth.

The domed end was interiorly coated with a polyvinyl chloride resin.Adhesive dispersions Nos. 1-7 were applied to the outer surface of theannulus by brush coating whereby an adhesive film of 0.002 inches thickwas applied to the annulus and then baked for 2 minutes in an oven setat 170° C. to evaporate the solvent and partially cure the epoxycomponent of the adhesive and partially fuse the thermoplasticcomponents. The end was then entered over the annulus of the necked insection of the body so that the annulus and lip sections of the end andbody members were in an overlapping relationship to form a lap joint.

Upon assembly the end and body members were moved axially relative toeach other to eliminate any pinholes or other defects in the appliedadhesive.

The assembled containers were then heated in an oven set at atemperature of 210° C. and held there for 2 minutes to fully cure andfuse the components of the adhesive mixture. The containers were thenremoved from the oven and air cooled to room temperature. Examination ofthe cooled containers indicated that the ends were securely bonded tothe container body.

The strength of the adhesive joint between the end and body members wastested by pressurizing the container to an internal pressure of 180 psi.At this pressure the walls of the container split open before anyseparation of the joint members occurred.

What is claimed is:
 1. An adhesive composition comprising a volatileorganic solvent having dispersed therein about 10 to about 70% by weightof a thermoplastic vinyl chloride polymer resin and about 5 to about 30%by weight of a thermosetting epoxy resin normally incompatible with thevinyl chloride polymer resin and an amount of about 20 to about 85percent by weight of an acrylonitrile/butadiene/styrene copolymer whichamount of copolymer is capable of imparting compatibility between theepoxy resin and the vinyl chloride polymer, the copolymer containingabout 10 to about 30% by weight acrylonitrile, about 10 to 30% by weightbutadiene and about 40 to about 70 percent by weight styrene.
 2. Theadhesive composition of claim 1 wherein the vinyl chloride polymer ispolyvinyl chloride.
 3. The adhesive composition of claim 1 wherein thevinyl chloride polymer is a vinyl chloride/vinyl acetate copolymer. 4.The adhesive composition of claim 1 wherein the epoxy resin isepichlorohydrin-Bisphenol A.
 5. The adhesive composition of claim 1wherein an aminoplast condensate is incorporated in the adhesivecomposition.